US SUPREME COURT DECISIONS

1. Where a reissued patent is granted upon a surrender of the original, for its alleged defective or insufficient specification, such specification cannot be substantially changed in the reissued patent, either by the addition of new matter or the omission of important particulars, so as to enlarge the scope of the invention as originally claimed. A defective specification can be rendered more definite and certain so as to embrace tire claim made, or the claim can be so modified as to correspond with the specification, but except under special circumstances, this is the extent to which the operation of the original patent can be changed by the reissue.

2. Where the patent was for a process of treating bark-tanned lamb or sheepskin by means of a compound in which heated fat liquor was an essential ingredient, and a change was made in the original specification by eliminating the necessity of using the fat liquor in a heated condition and making, in the new specification, its use in that condition a mere matter of convenience and by inserting an independent claim for the use of fat liquor in the treatment of leather generally, the character and scope of the invention as originally claimed were held to be so enlarged as to constitute a different invention.

3. The action of the Commissioner of Patents in granting a reissue within the limits of his authority is not open to collateral impeachment, but, his chanrobles.com-red

Page 93 U. S. 461

authority being limited to a reissue for the same invention, the two patents may be compared to determine the identity of the invention. If the reissued patent, when thus compared, appears on its face to be for a different invention, it is void, the commissioner having exceeded his authority in issuing it.

4. Klein v. Russell, 19 Wall. 433, stated and qualified.